Livestock Manure Recognized as a Highly Valued Crop Input

CANADA - New nutrition strategies, improved application technologies and the increasing costs of commercial fertilizer are prompting crop producers to recognize livestock manure as a highly desired commodity within an environmentally sustainable agricultural system.
calendar icon 30 June 2007
clock icon 9 minute read

Adapting and innovating for change was the focus of Manure Management 2007, a three day conference held last week (June 25-27) in Winnipeg.

The conference brought together leading experts from across North America and Europe to discuss a range of issued related to sustainable livestock production, including environmental regulations, phosphorus reduction strategies and the latest developments in manure treatment and application technologies.

Hog Manure Applications Improve Soil Quality

Randolph, Manitoba based Henervic Farms, a hog and grain operation, reports substantial improvements in the quality of the soil over the past ten years by replacing commercial fertilizer with hog manure fertilizer.

Ed Peters says, as the hog operation has expanded, the farm has moved almost exclusively to using hog manure to fertilize its crops. “The obvious reason is that there is manure that’s produced by these animals and you have to get rid of it somewhere. We’ve been in dairy and in hogs for many years and realized the huge value in manure being applied to our heavy clay soils and the improved tilth so we’ve really concentrated on looking at it as a real asset, as a resource in our farm.”

He explains, “Our cropping is based on the manure really. We grow winter wheat which is grown on areas where we need to apply manure early. We’ll grow corn which generally can not take manure that year because it’s harvested so late and yet we also grow all our corn on manured land without applying any fertilizer.”

Hog Manure Offers Similar Yield Response Superior Soil Benefits

Peters recognizes, “You can get a similar yield response with commercial fertilizers but the tilth of the soil, where our organic matter has risen about one and a half points from 3.3 to five parts of organic matter in the last 10 years seems to really make a big difference, even how it absorbs water and those kinds of things and its tilling ability.”

He credits the organic matter in the manure itself and says an additional factor is. when growing better crops, more residue results. “We’ve never burnt residue. We always grow it and chop it up. With the corn that we’re growing now there’s a lot of residue and that just works its way in and over the years it just improves it [the soil].”

Costs Associated with Manure Similar to those of Commercial Fertilizer

Peters admits that there is a “saw-off” on cost because manure pumping isn’t cheap, especially over longer distances. He says that within a mile manure application is generally the cheaper option, but when pumping three or four miles it is more expensive than commercial fertilizer.

However he stresses, “If we want to raise pigs we have to get rid of the manure. And if we didn’t have the land it would still cost us just as much to get rid of it and so, in that way, it’s a complete benefit. But, if your break it down, it still does cost us the amount that it would cost us to use commercial fertilizer.”

New Manure Management Regulations Alter Manure Application

One of the biggest and most recent changes in the use of livestock manure has been the Manitoba government’s decision to require livestock manure to be applied based on its phosphorus as well as its nitrogen content, depending on nutrient residual levels in the soil, rather than just nitrogen.

If phosphorus levels are below a 60 parts per million of sodium bicarbonate extractable phosphorus, then nitrogen is the basis for application. Above that threshold in the soil, then the phosphorus content of the manure must be considered.

Manure's Nitrogen to Phosphorus Ratio Typically Out of Balance for Crops

“Typically manure nitrogen to phosphorus ratios are much lower than what crops require,” says Dr. Mario Tenuta, Canada research chair in applied soil ecology with the University of Manitoba’s Faculty of Agricultural and Food Science.

“The nitrogen to phosphorus ratio can be anywhere from three, up to 15 to 20 depending on the type of manure, what’s added to the manure, if it’s a liquid based manure, if there’s straw added. So it’s very difficult to provide typical nitrogen to phosphorus ratios for manure. They do vary quite a lot but, I would say, typically some hog manure for example can range from four anywhere up to 15 depending on the solids content.”

Phosphorus Key to Animal Health

One of the factors behind the high amount of phosphorus in livestock manure is the fact that phosphorus is a key component of animal health.

Dr. Martin Nyachoti, an associate professor with the University of Manitoba’s Department of Animal Science explains, “Phosphorus is one of the key nutrients and it’s found in all life-forms. It’s required by all livestock because it’s one of the main nutrients for bone formation for example. So it’s very important. We must supply it. It’s one of the essential nutrients.”

The problem, Dr. Nyachoti points out, “The phosphorus that is present in the feed ingredients is not available to all animals, particularly pigs and poultry, because it’s bound in a form that’s known as phytate phosphorus. Pigs and poultry do not produce enough enzyme [phytase] that is required to break down that phytate phosphorus so for that reason not all of it is available to the animal.”

He estimates, “Mostly in grain feeds anywhere from 60 to 70 percent of the phosphorus is in this form of phytate, so it isn’t readily available.”

Nutrition Offers Option for Better Balancing Nitrogen Phosphorus Ratios

There are several strategies available to help bring the nitrogen phosphorus ratio into better balance says Nyachoti. One of the most widely used strategies currently is the enzyme phytase.

Dr. Nyachoti explains, “[Phytase is] the enzyme that breaks down the phytate phosphorus and makes it available.”

Another strategy is to use feed ingredients like distillers grains with high levels of digestible phosphorus. Nyachoti notes that there are other feed ingredients becoming commercially available that also have highly available phosphorus and that when they become widely available as commercial ingredients they will go a long way in enhancing phosphorus utilization.

Preserving Nitrogen Improves Nitrogen Phosphorus Balance

Another strategy that can be used to improve the nitrogen-phosphorus balance is to minimize nitrogen loss from the manure.

Dr. Tenuta suggests, “Going to a phosphorus based recommendation means that producers really want to conserve the nitrogen in their manure.”

He explains that nitrogen can be lost in several ways. “The first would be loss directly to the atmosphere as ammonia upon application; so we have ammonia volatilization. Another loss would be through greenhouse gas emissions or through processes such as denitrification where we have nitrates that would be produced from the manure being lost to the atmosphere through greenhouse gases. And the other one would be leaching of nutrients such as nitrate to the ground water.”

To contain that nitrogen in the manure, he recommends, covering manure storages to prevent ammonia losses and when applying to the land getting the manure incorporated into the soil as soon as possible. Dr. Tenuta also says that timing, in terms of weather conditions, can be a major factor.

“Under very hot dry conditions we can promote volatilization –that’s the loss of ammonia from manures – and so applying during cool humid conditions and getting that manure into the ground would prevent those losses of ammonia.”

Improved Application Technology Maximizes Manure's Benefits

Doug Redekop, the president and general manager of Precision Pumping, a company that provides custom livestock manure application services, agrees. “The people that are receiving the manure want to see it become as complete a replacement for commercial fertilizer as possible. And so we have to adapt equipment that is able and willing to go into a multitude of different soil and cropping conditions.”

He notes there has been tremendous change in the way manure is applied to the soil. “I think the big thing is the movement away from winter spreading and having storages that are capable of holding 400 plus days of manure so that you’re getting away from that daily or monthly application. Also, you want to inject the manure wherever possible so that you can keep that nitrogen phosphorus ratio in check.”

Redekop points out that there is a wide range of injector options available. “It can be very simple from a typical shovel type injector to a knife to a tyne to a coulter. There’s a wide range of injection types of equipment and also I’d say a wide range of acceptance too.”

Economic Viability of Manure Application Continues to Improve

Redekop observes, “As the cost of commercial fertilizer has gone up so has the value of the manure. I think we’re getting to a position now where the value of the manure can at least be equal to the cost of application if not a little greater, depending on the rates you’re putting on.”

He doesn’t expect that to change soon. “I would think that sheer demand is increasing the cost of fertilizer. You get countries like India and China that are demanding more commercial fertilizer to increase their productivity. So I can’t see commercial fertilizer costs going down anytime soon.”

Changes Expected to Improve Manure Use

Dr. Tenuta is confident the changes will allow producers to better conserve the nutrients in their manure. “They’re valuable. It costs a lot of money to make nitrogen. Cost lots of fossil fuels to make nitrogen, transport it, to purchase it. And therefore anything we can do to prevent its loss and make sure it gets to our crop is going to be a good thing.”

He views this as a wonderful opportunity to tighten nutrient cycling, to conserve nutrients making sure they get to the plant and don't get lost to the atmosphere or water.

He predicts, “In the next few years we’re going to have some interesting new applications, technologies, practices that are really going to help producers retain the nutrients in these manures.”

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